In fast, the 37-year-old former Sabrina the Teenage Witch star has lots of juicy and titillating revelations about Hollywood stars like Britney Spears, Drew Barrymore and even 'N Sync!

Here are Hart's top five most surprising stories from her new tell-all.

1. Drew Barrymore's Movie Set Makeout Session: Back in 1985, Hart costarred with Barrymore in the TV movie The Adventures of Con Sawyer and Hucklemary Finn. "Though I was only nine at the time, Drew was ten and still in her contentious, wild child, dope-smoking stage," Hart writes. "One day, she took the group behind our motel to watch her give a French-kissing lesson with costar Kimber Shoop, who went on to play the title role in The Ted Kennedy Jr. Story (yup, a TV movie). I'm bummed to report that she didn't let me come watch her wiggle her tongue in Kimber's mouth, because I was a year younger than her, but she did teach me how to backstroke in the motel pool."

2. Calista Flockhart Does Eat! While working with her "first girl crush" Calista Flockhart in the Broadway play Beside Herself at age 13, Hart witnessed the waify actress's big appetite firsthand when they ate at John's Pizzeria in NYC. "Mom, Calista and I could each eat a whole pie by ourselves," she reveals. "Years later, when Calista was rumored to have an eating disorder, I was tempted to leak shots of us surrounded by some big old pies to prove the gossipers wrong."

3. Hart's 'N Sync Party Past: Who knew that Justin Timberlake and JC Chasez were party pals with MJH? In fact, one vacation in particular saved Hart from 9/11. "No travel memory, however, compares to when 'N Sync, who did a cameo on the show in 1999, asked me to join them in Turks and Caicos at the end of their 2001 summer tour," Hart writes. "In the Caribbean, we had a great time sipping fruity drinks and partying with some other celebrities like Tori Spelling and Olympic medalist Tara Lipinski. The boys took off for the States on September 10, while the rest of us hung back to worship the sun a little longer. The next day, planes hijacked by terrorists struck the Pentagon and New York City's Twin Towers."

4. Backdoor Britney: Hart recounts working with Spears for her movie Drive Me Crazy in the late '90s. Hart says Spears, who was underage at the time, was being micromanaged by her team, who wouldn't let her stray from her busy schedule for even one lunch date. "I devised a plan to sneak her out of her hotel and then take her dancing so she could chill with people closer to her age, if just for one night. Britney loved the idea," Hart says. After lying to Spears' bodyguard, they drove to L.A.'s Club Cherry where they were snuck in through the back door. "But once we got inside, Britney got absorbed by the crowd, and I lost her," Hart explains. "At the end of the night, I found her in a private booth with dozens of people kissing her ass as she basked in the attention and down time she'd worked so hard for...Since then, Britney's been snuck in and out of more back doors than I can count, but I shudder to think that I first showed her how it's done."

5. Getting Back at Jerry O'Connell and His Wandering Eye: Writing about running in to her former classmate Jerry O'Connell at the Kentucky Derby in 2002, Hart recounts, "Jerry hardly showed me any attention when we were at school or bumping into each other around Manhattan, but that night, he followed me around like a puppy dog...If experience taught me anything, it's that charismatic flirts are rarely boyfriend material—and Jerry sure thought a lot of his own charms. I also wanted to give him a taste of his own standoffish medicine, since he pretended to barely notice me for four years even though we saw each other all the time."

Honorable Mentions: Hart's first onscreen kiss was James Van Der Beek, she turned down the Newlyweds show that later went to Jessica Simpson and Nick Lachey, Oscar de la Hoya once tried to lure her back to his house, Tara Reid was once her naughty BFF in school and her Dancing With the Stars partner Mark Ballas gave up on her during her stint on the show.

Your information may be shared with other NBCUniversal businesses and used to better tailor our services and advertising to you. For more details about how we use your information, see our Privacy Policy. If you are located outside of the U.S., your information may be transferred to, processed and used in the U.S.